1. Field of the Invention
The present invention relates to an apparatus for dissolving noble metals, wherein chlorine gas (Cl2) produced electrochemically is converted into an adequate chlorine compound depending on the particular types of noble metals so that the noble metals are dissolved effectively, and materials for use in dissolving the noble metals form a closed system.
2. Description of Related Art
In general, noble metals having high redox potentials react with a high concentration of oxidative acid, such as aqua regia, at high temperature and are dissolved therein. In this case, a large amount of acid is required due to the continuous consumption of acid. Further, treatment of the waste liquids and harmful gases generated during the reaction may entail environmental problems.
In addition, existing chlorine-based dissolution processes for dissolving platinum metals, such as rhodium or ruthenium, which may not be dissolved in aqua regia include injecting chlorine gas stored in a high-pressure gas container into a reactor. Thus, since the gaseous chlorine should be treated in the exterior of the reactor, the overall system becomes complicated and may cause safety-related problems.
To solve the above-mentioned problems, we have filed three patent applications, the disclosures of which relate to an electroleaching system for producing chlorine gas via the electrochemical oxidation of a chloride-containing solution, leaching a noble metal by the chlorine gas, and recovering the noble metal by reducing the leached noble metal in a reduction chamber using a separation membrane; an electroleaching system including a separation/purification unit by which only the noble metal is separated and purified, and then transferred to the reduction chamber; and an electroleaching system in which production of chlorine gas and leaching and reduction of the noble metal are carried out in a single unit divided by a membrane (Korean Patent Publication Nos. 1006613060000, 1007535870000 and 1006839610000). However, it is difficult to recover volatile noble metals using the known apparatuses. Under these circumstances, it is required to dissolve noble metals by introducing the most adequate chlorine compound to a noble metal depending on the particular type of the noble metal so as to improve the dissolution rate of noble metals and thus the recovery of dissolved noble metals. In addition, there is a need for developing an eco-friendly, safe and economical apparatus for dissolving noble metals, which generates no waste liquids or waste gases and forms a closed system.